Hydraulically actuated swing boom crane



Nov. 7, 1950 H. wuNscH 2,528,985

HYDRAULICALLY ACTUATED SWING BOOM CRANE Filed Jan. 22, 1947 's Sheets-Sheet 1 I6 17 L2 7 25 T u nun-mum INVENTOR Harry Wunsch TTORNEY Nov. 7, 1950 H.- WUNSCH HYDRAULICALLY ACTUATED SWI [NG BOOM CRANE 5 SheetS-Sheet 2 Filed Jan. 22, 1947 \NVENTOR Harry Wunsch Y ORNEY Nov. 7, 1950 H. wuNscH 2,528,985

HYDRAULICALLY ACTUATED SWING BOOM CRANE Filed Jan. 22, 1947 I5 Sheets-Sheet 3 INVENTOR Harry Wun'sch BY Patented Nov. 7 1950 UNITED STATES PATENT OFFICE 2,528,985 'HYDRAULICALLY ACTUATE'DSWINGBOOM V CRANE Harry Wunsch, Brooklyn,N. Y. Application January 22, 1947, Serial No. 723,608

1 It has been customary to swing a crane boom from side'to side by means of mechanism including gears in spite of the objection to gear and the difliculty of keeping the gears and bearings imalinement' due to the distortions attendant upon the movement of the supporting 'frame, and the Swinging and bobbing of the boom" especially on automotive cranes. I

Hydrauliccy-linders are cheap and reliable and commonly used for exerting force in various ways and would seem to be suitable for such work. In fact, the use of an hydraulic cylinder and piston has been suggested but a piston rod and crank on the mast tend to stall-on a dead center so that a single cylinder is objection-able.

I have overcome this'difiiculty by'the use of two hydraulic cylinders and pistons hinged and connected with the boom either directly or indirectly from themastand provided with a'pump and controlvalve so thatthe boom can be swung approximately 90 or more to each side from its center position. This system is capable of continuous hard-use'witha minimum of interference.

Fig, l is a plan view showing'one arrangement of two cylinders'and pistons for controlling the swinging of a boom on a vehicle such asa portable crane or hoist. i

"Fig. 2 is a side view of a fragment of a mast and boom with the connected cylinders and pistons.

3flis' a diagrammatic view showing the arrangement of an hydraulic system for controlling the mast and boom.

i Fig. 4 is aside elevation and partial section-of a hinge support'forthe two cylinders. I

Fig. '5 has diagrammatic outlines showing the relative positions of the cylinders and their pistons in swingingfrom one extreme position to another 180 apart. p v I Fig. dshovys diagrammaticviews of the valve forthe lower cylinderinthe positions corresponding to the positions of the cylin'der in-the'diagram .5 d e1yl b 1 e 4 Fig. 7 shows diagrammatic views of the-valve for the upper cylinder in the positions corre- 4 Claims. (01. 212:66)

2 ported in arms l7, l8 and I!) in any suitable manner.

Pistons of any suitable type have rods such as and 2| hinged to crank arms 22 and 23 respectively, which are connected to or formed as a part of the hanger I3 which carries the boom. It will be seen that cylinder [5 is mounted to swing in a'pl'ane above cylinder I4. Thisis necessary in order that the cylinders and their pistons and respective crank pins 'can'cleareach other as the mast is rotated from one extreme to the other as indicated in the diagram of Fig.5.. A tank 25 contains a supply of suitable liquicl such as oil which is forced throughthe system by a power driven pump 26 and-its flow controlled by -a-3-way manually actuated valve 2'! usually spring centered. The pu'mp maybe of any suit- 'sponding to the positions of that cylinder in the diagram Fig. 5 above.

Fig; 8 is a diagrammatic view of. a pilot valve controlled system for actuating the valveforone' tion of valve 21.

able type Which will provide fluid under'pres'sure such as a rotary vane pump. Quick actin over center cam tripped valves A and 'B are connected between the ends of the cylinders" and to the load pipe lines LI and L2 which are connected to valve 21. With the valve 27 inthe position of Fig. 3'and the pump actuating, liquid will be forced through'thepipe line'Ll and the valves A and B in such a manner as to rotate the mast and boom in an anti-clockwise direction. By turning the valve 2l'so that'the pump discharge will pass through line L2, the rotation of the mast and boom will be reversed. A check valve 29 may be interposed between the pump 26 and valve 21.

' Fig. 6 shows the positions'a, b, c,.d, and e of the valve A with respect tothe lines LI and L2 and the head end and crank end of the cylinder [4 corresponding to the positions a, b, c, d, e of the cylinder shown above each valve sketch in Fig. 5, and Fig. '7 shows the corresponding positions (1.1), c, d and e of the valve B with respect to the pipe lines LI and L2 and the head and crank ends of the cylinder l5. In position d of valve A for cylinder 14 the valve A is just snapping over from position cto positione and in position b of valve B forcylinder 15 the valve B is just snapping over from position a to position c. I

It will thus be seen that high pressure liquid may be applied tothe system through'either pipe LI or L2 'andreturned to the tank 25 through the reverse l'ine L2 or LI depending upon the posi- The crank connections are set at such an angle to each other and with respect to the mast as an axis, that when one cylinder goes through dead center the other is operating at'or near a maximum radius. When a cylinder passes dead center it automaticallytrips its in-. dividual valve (A or B) which reverses the pressure from the head end to the crank end of the cylinder or vice versa depending upon the direction of rotation. The automatic trip valve may be of any suitable type either mechanical or an 3 electrically control-led solenoid or a hydraulic pilot valve.

The cylinders may be hinged at any convenient location either on a common axis or separately, depending upon the layout of the other mechanism. The location of the crank arms 22,

and 23 with respect to the direction of application of pressure by the piston rods should be'such that when one piston is pressing on its crank pin at dead center the other piston is pressing on its crank pin at its most effective angle. means that with th cylinders mounted on a common axis as shown, the crank arms would be arranged at approximately right angles to each other. This relation of the crank arms however may be varied according to the location of the pivots of the cylinders so long as the possibility of dead center effect is avoided as above pointed out. The direction of motion of the mast and boom is controlled by simply shifting the valve Z'I- -the rest of the operation being automatic. The cylinders being double acting are each efiective. 1

There are several ways in which the over the center action can be effected. Fig. 8 shows a diagram of a pilot valve system. Valve B is fed from valve 2! through pipes Li and L2 and controls the liquid pressure to the opposite ends of cylinder IS, The actual tripping action is effected by a standard pilot valve 30 which obtains pressure from the pump 26 which is always avail- ThiS 4 carried by said means, said rotatable supporting means including two crank arms extending radially from the axis of saidsupporting means in planes diverging at an acute angle to each other, a hinge connection at the outer end of each arm, said hinge connections being movable in parallel planes spaced about from each other vertically,

and hydraulically actuated means for rotating said supporting means including two cylinders,

able because the pilot valve 36 is connected between the pump 26 and the spring loaded check valve 29. The pilot valve '30 controls the main valve B which actually handles the main body of fluid to the cylinder l5. Valve A is actuated in a similar manner to control cylinder [4. The arrowsin Fig. Sindicate connections to the valve A and its pilot valve (not shown). Valve 21 is actuated by hand.

Another method of obtaining the over the center action isshown in the' diagram of Fig. 9. Valve 21 of course is actuated by hand and directs the liquid pressure thru pipe Ll or L2 to valves A and B depending upon which direction of rotation of the boom is desired. The over the center action of Valve A is effected by the rod 3!. This rod is connected by the rocker 32 to the valve rod 33 and is actuated by another 7 I rocker 34. A projection 35 rotated on or by some part of the mast H or boom tilts the rocker 34. The other end of rocker 34 engages a slide 35 on rod 3| which is compressed between two springs 37, 3'! on'the rod 3|. engages a notch 39 in rod 3| and thus resiliently holds the rod and connected parts in a given position. When the rocker 34 is tilted clockwise sufiiciently to compress the upper spring and Spring pressed roller 38,.

overcome the pressure of roller 38 in notch 39, r

the rod will jump so that roller 38 will be retracted and will drop into notch 4llthus moving the valve stem 33. I

The over center snap action of valve B is similarly effected by a projection'35' carried by or means for supporting 'said cylinders to turn in said respective parallel planes, a piston in each cylinder having a piston rod connected to its respective hinge connection and hydraulic means for actuating said pistons and turning said supporting means. 1

'2. A hydraulically actuated swing boom crane comprising a rotatable supporting means, a boom carried by said means, said rotatable supporting means including two crank arms extending radially from the axis of said means in planes di-' verging at an acute angle to each other, a' hinge pin at the outer end of each arm, said hinge pins being movable in parallel planes spaced'apart from each other vertically, and hydraulically actuated means for rotating said supporting means including two cylinders mounted on a common post to turn in said respective parallel planes, a piston in each cylinder having a piston rod connected to its respective hinge pin, and hydraulic means for actuating said piston and turning said supporting means. I

3.. A hydraulically actuated swing boom crane comprising a rotatable supporting means, aboom carried by said supporting means, said rotatable supporting means including two crank armsextending radially from the axis of said means in planes diverging at an acute angle to each other, a hinge connection at the outer end of eacharm,

said-hinge connection being movablein parallel planes spaced apart from each other vertically;

hydraulically actuated means for rotating said supporting means through approximately at least to the right and left from a central position including two cylinders, means for supporting said cylinders-to turn in said respective parallel planes, a pistonin each cylinder having a piston rod connected to its respective hinge connection and a pump and valve system for actuating said pistons including snap action mechanism for car.- rying each cylinder over the dead center while the boom is turning.

4. A hydraulically actuated swing boom crane comprising a rotatablemast, a yokefastened'to the mast, a pair of arms on said yoke diverging from each other on difierent horizontal planes,

HARRY WUNSCI-II.

REFERENCES CITED The following references are of record in the file of this patent;

UNITED STATES PATENTS Number Name Date 884,307 Winemiller et al Apr. 7-, 1908 1,553,063 vBedgood Sept. 8, 1925 -1,783,'78'7 Hansen Dec. 2, '1930 Arps et a1, "n w"..- Jan; 1.19456 

